If the distribution of the height of American men is approximately normal, with a mean of 69 inches and a standard deviation of 2.5 inches, then roughly 68 percent of American men have heights between __________ and __________.
A . 64 inches and 74 inches
B . 66.5 inches and 69 inches
C . 71.5 inches and 76.5 inches
D . 66.5 inches and 71.5 inches
Answer: B